ASTRONOMY 101

Mesa College

Fall 2002

Fifth Examination

NAME______________________________(Print) Lec. hr.______ days class meets______

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1 The sun's position relative to the center of our galaxy was correctly determined from a study of the space distribution of

a. O-and B-type stars d. M-type main sequence stars

b. globular star clusters e. interstellar dust clouds

c. supernova

2 The general spiral structure of the galaxy has been confirmed by

a. the Doppler effect in starlight from stars in the plane of the Milky Way

b. the distribution of globular clusters in space

c. the distribution of RR Lyrae variables in the plane of the Milky Way

d. 21-centimeter radiation from cold hydrogen gas clouds in space

e. the concentration of dust clouds in certain directions in space

3 Which of the following is a property of spiral galaxies?

a. highly flattened

b. pinwheel-shaped features consisting of bright stars

c. relatively large quantities of dust and gas between the stars

d. all of the above

4 Elliptical galaxies are probably older (in years) than spirals.

a. true b. false

5 Population I stars are defined as stars located in the

a. halo of the Galaxy c. disk of the Galaxy

b. nuclear bulge d. outside the Galaxy

6 The mass of the Galaxy is determined by

a. counting the total number of stars within it.

b. star gauging.

c. evaluating the gravitational influence of the system as a whole on the

sun or other orbiting objects .

d. mass analysis.

7 The most massive of galaxy type is:

a. giant elliptical b. spiral c. dwarf elliptical d. irregular.

8 Irregular galaxies are

a. amorphous patches of stars and gas

b. small spiral galaxies

c. small elliptical galaxies

9 For distant galaxies, if one galaxy is twice as far as another, then its velocity of recession will be

a. 1/2 the nearer one b. 4 times greater than the nearer one

b. 2x the nearer one d. they are both are equal to each other

10 Most astronomers today agree that the red-shifts of the spectra of distant galaxies represent

a. cooling of the universe

b. rapid contraction of the universe

c. rapid expansion of the universe

d. failure of physical laws at great distances

e. intergalactic absorbing dust

11 Hubble discovered a highly significant relationship between two observable quantities (data) for exterior galaxies. The quantities are

a. red shift and distance

b. red shift and velocity

c. velocity and apparent brightness

d. red shift and apparent brightness

12 The type of galaxy that exhibits the largest range in mass and size is the

a. barred spiral c. normal spiral

b. elliptical galaxy d. irregular galaxy

13 A super cluster of galaxies is a cluster made up of super massive galaxies.

a. true b. false

14 The mysterious "dark matter" is thought to exist because it

a. provides gravitational force but does not emit light

b. blocks the view of more distant H II regions

c. blocks the view of more distant galaxies

d. reddens the light from more distant galaxies

e. reddens the light from more distant stars

15 The most likely explanation at present for the luminosity of quasars pictures that radiation as coming from

a. matter spiraling toward a super massive black hole

b. matter falling only many neutron stars

c. nuclear reactions in interstellar gas

d. intense cosmic rays interacting with spiral arms

e. annihilation of matter and antimatter in spiral arms

16 A Seyfert galaxy is thought to be related, in terms of life cycle, to quasars.

a. true b. false

17 The fact that quasars can vary considerably in brightness in a week or less indicates that

a. much of the energy comes from a relatively small region

b. quasars are very far away

c. quasars are very large

d. quasars must be breaking apart

e. quasars must have large redshifts in their spectra

18 Why were quasars called quasi-stellar sources?

a. They looked like stars on photographs.

b. They are ordinary (but very luminous) stars located at vast distances from Earth. c. Their spectra strongly resemble those of stars.

d. They are stars which emit very strong radiation in the radio.

19 The Local Group is:

a. The small cluster (group) of galaxies to which the Milky Way belongs.

b. The region of the Milky Way which contains Andromeda and several other spiral nebulae.

c. One of the largest clusters of galaxies known.

d. The nearest group of stars to the Solar System.

20 The cosmological principle states that the universe, on a large scale, appears the same from any location, at the same moment.

a. true b. false

21 Assuming the Big-Bang theory is correct, the crucial factor which will determine whether the universe is open or closed is

a. the presence or absence of black holes

b. the black-body radiation law

c. the mean density (or total mass) of the universe

d. the speed of light

22 The approximate accepted age of the universe is believed to be about

a. 10 million years c. 5 billion years

b. 1 billion years d. 15 billion years

23 Which of the following was not created in the Big Bang?

a. hydrogen b. iron c. helium

24 The 3 Kelvin radiation is believed to be

a. the combined light from distant stars

b. the combined light from distant galaxies

c. the remnant of the early days of the universe

d. the red shifted radiation from quasars

25 An example of a closed geometry would be

a. a table top

b. space which curves away from itself

c. space which curves into itself like a ball

26 Evidence that there may have been an exploding primeval fireball that initiated the expansion of the universe comes from

a. the discovery that the universe is bathed in low energy microwave

radiation (2.7 K)

b. the observed explosions of certain galaxies

c. the nonthermal radiation (synchrotron radiation) of the quasars

d. the discovery of antimatter in distant space

27 The results of the COBE mission was to

a. discover the first planets orbiting distant star systems.

b. discover the cause of the formation of our solar system.

c. determine the elements found in distant interstellar clouds.

d. find the first evidence of galaxy formation.

28 In general, galaxies are found in space by themselves, that is, not in clusters of galaxies.

a. true b. false

29 It is thought the elliptical galaxies are evolved from spiral galaxies.

a. true b. false

30 In the context of the Big Bang theory, inflation involves

a. a sudden increase in the temperature of the cosmic background radiation.

b. sudden increases in the temperature and density of the Universe.

c. sudden expansion in the size of the Universe.

31 A universe that will eventually stop expanding and collapse back in upon itself(just once) is a(n)

a. closed universe c. oscillating universe

b. inflationary universe d. open universe

32 The Top-down model of the universe says that

a. planets were formed first and then stars.

b. galaxies formed first and the clusters of galaxies and superclusters later.

c. great clouds of material formed from which superclusters formed.

33 The Bottom-up model of the universe says that

a. planets were formed first and then stars.

b. galaxies formed first and the clusters of galaxies and superclusters later.

c. first, great clouds of material formed from which superclusters formed.

34 The force that holds the atomic nucleus together is

a. electromagnetic b. gravity c. strong nuclear d. weak nuclear

35 The force that holds a metal bar together is

a. electromagnetic b. gravity c. strong nuclear d. weak nuclear

36 The force that holds stars together is

a. electromagnetic b. gravity c. strong nuclear d. weak nuclear

37 An estimate age of the universe can be made from a study of the

a. age of the oldest rocks on the Earth

b. uranium decay

c. Hubble constant

38 In regards to galaxies, what does the mass to light ratio tell the astronomer?

a. its distance

b. its chemical composition

c. its shape

d. whether star formation is going on or not

39 Inflation explains why the cosmic background radiation is so similar in all directions.

a. true b. false

40 An example of a closed geometry would be

a. a table top

b. space which curves away from itself

c. space which curves into itself like a ball

Describe the phenomena known as gravitational lensing. Be sure to include its cause. 2 points

Stars in globular clusters started out with a core of approximately 75% hydrogen. They now contain a much lower percentage of hydrogen. What happened to the hydrogen? 2 points

Describe the large scale distribution of galaxies in the Universe. 2 points

Describe the unusual behavior of the center of the nucleus of our galaxy. 2 points

For a galaxy in a cluster of galaxies, discuss how its mass & shape might change over time.

2 points

Describe, in a general way, describe the creation of our galaxy. 2 points

Describe two methods of determining the distance to a galaxy. 4 points

Make diagram of our Galaxy & indicate & label the locations of the following: central bulge, corona, disk, halo, & spiral arms. 5 points

Describe the basic difference between an open & close universe. 2 points

In very general terms, describe the creation of our galaxy. 3 points

How do active galaxies differ from normal galaxies? 2 points

Describe the phenomena known as gravitational lensing. Be sure to include its cause. 2 points

Describe the behavior of the center of the center of the Milky's galactic nucleus. 2 facts 2 points

Describe two methods of determining the distance to a galaxy. 4 points